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The main section of the project involved a study of the electrochemical behaviour of the 1-phenylazo-2-naphthol system, some of which were found to form diphenylamine type products whilst some were found to dimerize upon electrolysis.1-Phenylazo-2naphthols undergo azo-hydrazone tautomerism, a phenomenon which was investigated by a wide range of analytical techniques. Much spectroscopic data including C n.m.r. (liquid and solid phase) and 360 DUiz N n.m.r. spectra were recorded and interpreted. The dyeing of fibres, light fastness tests and computational studies were also performed on these coloured molecules. Other conjugated systems investigated by electrochemical and chemical oxidative techniques included phenothiazines, azo-triazoles, azo-benzenes and furfurylidenimines.

The lithiation and subsequent condensation with an electrophile is a useful reaction in many 'total' syntheses. This study was undertaken to investigate the lithiation reactions of several organic molecules. In Chapters 2 and 3, the lithiation of a range of <I>N-</I>pivaloyl-<I>o</I>-toluidines was studied, with the resultant formation of indoles (Chapter 2) and reaction with carbon monoxide to form a carbonylated product (Chapter 3). The lithiation reaction was then applied to 2,5-dimethyl-1,4-phenylene-di-<I>N</I>-pivaloylamine as an attempt to effect quadruple lithiation. However, only double lithiation was observed. In Chapter 4, the attempted lithiation of trifluoroacetylanilines, was studied to see whether it is possible to effect lithiation on the aromatic ring to yield a dianion. Both alkyl and aryllithium reagents were observed to act as nucleophiles towards the substrates, resulting in displacement of the trifluoromethyl group. In Chapters 5, 6 and 7, lithiation of pyridones was investigated. Lithiation and electrophile trapping were found to readily occur for 3-methyl- (Chapter 6) and 6-methyl-2-pyridone (Chapter 5). However, the research on 4-methyl-2-pyridone (Chapter 6) showed that <I>n</I>-butyllithium caused either (i) lithiation at the 4-position in the ring or (ii) acted as a nucleophile, with the addition of a butyl group at the 6-position in the ring. The reaction of <I>n</I>-butyllithium and 3-cyano-6-methyl-2-pyridone was studied (Chapter 7). <I>n</I>-Butyllithium was found to act as a nucleophile towards 3-cyano-6-methyl-2-pyridone, resulting in the addition of a butyl group.

The work described in this thesis outlines the achiral synthesis of lignans and their oxidation. Chapter one classifies lignans and examines their natural occurrence and biological activities. The biosynthesis and synthesis of lignans is also reviewed. Chapter two describes the selective synthesis of <I>trans</I>-dibenzylbutyrolactone lignans. Tandem conjugate addition to 2(5<I>H</I>)-furanone utilising diphenyl thioacteals as acyl anion equivalents, followed by <I>in situ</I> trapping with aromatic benzyl bromides, afforded the adducts in good yields. Desulfurisation yielded the <I>trans</I>-dibenzylbutyrolactone lignans, including enterolactone and matairesinol. The biological activity of some <I>trans</I>-dibenzylbutyrolactone lignans is also discussed. Chapter three describes the non-selective synthesis of <I>cis</I>-dibenzylbutyrolactone lignans. An Aldol reaction with a substituted aromatic aldehyde, followed by acetylation and treatment with NaH, afforded the corresponding α,β-unsaturated lactones in good yields. Subsequent catalytic hydrogenation yielded with <I>cis</I>-dibenzylbutyrolactone lignans as the major product. Chapter four describes the selective oxidative cyclisation of <I>trans</I>-dibenzylbutyrolactone lignans using RUTFA, PIFA and DDQ to afford dibenzocyclooctadiene lignans. The non-selective oxidative cyclisation of <I>cis</I>-dibenzylbutyrolactone lignans was also carried out using the same reagents. It was also shown that cyclisation of <I>para</I>-hydroxy-dibenzylbutyrolactone lignans occurs <I>via</I> a spirodienone intermediate with PIFA is employed. Chapter five describes the selective oxidative cyclisation of <I>trans</I>-dibenzyltetrahydrofuran lignans. Reduction of the <I>trans</I>-dibenzylbutyrolactone lignans, and subsequent dehydration of the resultant dibenzylbutanediols, afforded the dibenzyltetrahydrofurans in good yields. These were successfully cyclised to dibenzocyclooctadiene lignans using RUTFA and PIFA. It was also shown that cyclisation of <I>para</I>-hydroxy-dibenzyltetrahydrofuran lignans occurs <I>via</I> a spirodienone intermediate with PIFA.

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